iMovie IOS exports but doesn't show in photos

I tried exporting my iMovie, but it wouldn't begin because it said there was not enough space on my device. So, I made just enough space be deleting some apps. Then it exported, but once the progress bar was complete, it then said there was not enough space to export. So I was going to make even more space and try again - but noticed a strange thing. iMovie (specifically its 'Documents & Data') were taking up an additional 7.4 gigabytes than they were before - which is the amount of gigabytes iMovie said my movie would be. The movie is also not in photos - it seems to be being stored in iMovie. Only I cannot get it out. If I try exporting again, it just says there isn't enough space on my iPad (which is due to iMovie taking up all that additional space due to it storing the previous export somewhere). So my question is not about how I can export the movie properly (I assume trying again but with well more space than it requires would work) but is instead how can I remove this video iMovie seems to have saved in its files? As it takes up a significant chunk of the data on my iPad and I cannot remove it.